I have updated the gallery in my previous post with some pictures of my v2 shield, which more completely covers the hot end and the wiring. I need to make some updates to the design (for example, the tunnel for the wires is too small), but it appears to be an improvement.
Things I've learned:
- You need to completely clean the inside of the shield and remove all traces of the vaseline, otherwise it will burn and cake on your hot end.
- The cornstarch trick for curing works. Go easy on it, it works really well. I'd suggest maybe 10-20% cornstarch mixed in.
- Tiewraps become brittle when kept warm.
- The shield made only a minor improvement in the quality of supported overhangs using the stock fan.
- Those big triangular paperclip things make excellent clamps.
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OK, I cooked my silicone shield for 30 hours in the rice cooker and it came out fine. https://www.dropbox.com/sh/ou1z52iwtq4hbtl/XhhmSoJJEN.
Interestingly, I got a bit of delamination on the mold, but not on the z-axis layers. Flakes of the surfaces in direct contact with the silicone detached (but were easily removed). One thing I did do is dip the mold in water after lubing it up with vaseline, in the hopes this would speed the cure.
I cut a rectangle out of the top of the shield so that the top edges overlapped the top of the hot-end, then punched holes for the heater and thermocouple wires, and added a slit up to the top so that the shield could be wrapped around the hot-end. I also had to chop off the bottom of the nozzle part to get adequate clearance.
After putting the shield in place I added a tie-wrap for extra security.
Temperature measurements (sorry for the mixed units) using the stock fan and duct at speed 255 with Z=0, using a crappy meat thermometer.
Hot End Off: 78F
Hot End On, No Shield: 92F
Hot End On @ 210C, Shield: 80F (!)
I'm currently doing an overhang print test to see if the shield actually makes a significant difference.
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